1. Field of the Invention
The present invention relates generally to tissue resection, and more particularly to methods and systems for resecting tissue after tissue necrosis.
Tissue and organ removal are required in a number of surgical procedures for a number of purposes. A major concern in all tissue removal procedures is hemostasis, i.e. cessation of bleeding. All blood vessels supplying an organ or a tissue segment to be removed have to be sealed, either by suturing or cauterization, to inhibit bleeding when the tissue is removed. For example, when the uterus is removed in a hysterectomy, bleeding must be inhibited in the cervical neck which is resected as well as along the vessels which supply blood to the uterus along its sides. Similarly, blood vessels within the liver must be individually sealed when a portion of the liver is resected in connection with removal of a tumor or for other purposes. The liver is a highly vascularized organ and sealing of the blood vessels is quite time consuming. Achieving hemostasis is necessary in both open surgical procedures and in minimally invasive surgical procedures. In the latter case, however, because of the limited access through cannula and other small passages, sealing of blood vessels can be even more time consuming and problematic.
Achieving hemostasis is particularly important in laparoscopic and other limited access procedures where the organ or other tissue must be "morcellated" prior to removal. Most organs are too large to be removed intact through a cannula or other limited access passage, thus requiring that the tissue be morcellated, e.g. cut, ground, or otherwise broken into smaller pieces, prior to removal. It will be appreciated that morcellation of vascularized tissue can be very problematic.
For these reasons, it would be desirable to provide improved methods, systems, and apparatus, for achieving hemostasis in connection with organ and tissue removal procedures. In particular, it would be desirable to provide methods and systems which permit a surgeon to achieve hemostasis in a time-efficient manner, using readily available surgical equipment (e.g. radio frequency power supplies as discussed below), while reducing risk and trauma to the patient. It would be further desirable if the methods and systems are applicable to a wide variety of tissue removal procedures, including at least hysterectomies, liver tissue resection, cholecystectomies, prostate removal, lung resection, and the like. It would be still further desirable if the methods could provide for complete or substantially complete coagulation and hemostasis of an entire volume of tissue to be removed in order to facilitate subsequent morcellation. The ability to morcelate tissue while minimizing bleeding will be of substantial benefit to the performance of laparoscopic and other minimally invasive procedures. At least some of these objective will be met by the invention described and claimed hereinafter.
2. Description of the Background Art
The use of radio frequency (RF) energy to necrose body organs or portions thereof is known. U.S. Pat. No. 4,979,948 describes a balloon electrode which is inflated in the interior of a uterus and used to apply RF energy to necrose the endothelial lining of the uterus. U.S. Pat. No. 3,845,771 describes a glove having flexible electrodes on the thumb and middle finger. The glove is intended for conducting RF current to conventional forceps, scalpels, etc. U.S. Pat. No. 4,972,846 describes electrode patch pairs useful as defibrillator leads which are engaged directly on the epicardium. U.S. Pat. Nos. 5,178,618 and 5,078,736 describe stents which can be energized to apply RF energy on the interior of a body lumen. Lorentzen et al. (1996) Min. Ivas. Ther. Allied Technol. 5:511-516 describes a loop electrode that can be rotated within tissue to excuse a tissue volume.